The Relationship Model between Traffic Volume and Traffic Conflict at the Merging Points of Urban Tunnel Entrance

Urban tunnel entrance section is the main danger zone. At the entrance, merging traffic triggers safety problem, so it is necessary to evaluate the traffic safety at merging area for urban tunnel. Currently, traffic conflict data are not sufficient to evaluate traffic safety level effectively through traffic conflict technique. In this paper, based on the condition that the number of traffic conflict is positively related to traffic volume, the relationship between traffic volume and traffic conflict is studied, and the relationship model between traffic flow and conflict at tunnel entrance merging area is built based on the following assumption: vehicle arriving frequency distribution is close to random distribution when traffic density is relatively low and is close to binomial distribution when traffic is congested. The model can be used to calculate the number of traffic conflicts based on traffic volumes, which improves the safety evaluation method based on traffic conflict technique. Finally, a case study is brought forward to prove the reliability of the model.